The present invention relates to a printer, and more particularly to a printer provided with a mechanism for winding up recording paper which has passed through a printing position of a printing head.
Generally, a printer for performing printing on rolled recording paper is mounted on a POS terminal or the like. In order to facilitate exchange and loading of the rolled recording paper by opening a transporting passage of the recording paper, which is formed between a printing head and a platen arranged close to and opposed to the printing head, there is known a printer of such a type that the platen and other members are mounted on a movable frame which can be opened or closed. There is also known a printer which is provided with a mechanisms for winding up the recording paper passed between the printing head and the platen, for the purpose of storing the printed recording paper.
In this printer, a winding shaft for the recording paper to be wound around is usually provided on the movable frame, because the winding shaft must be taken out on occasion for exchanging the wound paper. Moreover, both ends of the winding shaft are fitted in grooves which are formed with the movable frame and opened upward, so that the winding shaft can be easily taken out. Such a configuration is disclosed in Japanese Patent Publication No. 10-101252A, for example.
One example of a printer having such structure will be described with reference to FIGS. 6A and 6B. As shown in FIG. 6A, a printer body 101 has a fixed frame 103 and a movable frame 104 which is attached to the fixed frame 103 through rotary bearings 109. The fixed frame 103 is further provided with a bucket 112 for accommodating rolled recording paper 102, and a printing head 108 for performing printing on recording paper 102a which has been drawn out from the rolled recording paper 102.
The movable frame 104 is provided with a platen 107 which is opposed to the printing head 106 and a fixed distance from the printing head 106 when the movable frame 104 is closed, a paper feeding roller 108 for transporting the recording paper 102a which has been drawn out from the rolled recording paper 102, and grooves 111 for receiving a winding shaft 105 which winds up the recording paper 102a that has passed the paper feeding roller 108. The winding shaft 105 is mounted so as to rotate with both ends 110 thereof set respectively in the grooves 111.
The recording paper 102a which has been drawn out from the rolled recording paper 102 is transported by the paper feeding roller 108, and printing is performed while the recording paper passes between the printing head 106 and the platen 107. Thereafter, the recording paper 102a is wound up by the winding shaft 105.
When the rolled recording paper 102 is to be exchanged, it is necessary to open the movable frame 104. When a user tries to open the movable frame 104 by more then 90 degrees as shown in FIG. 6B, however, the winding shaft 108 may fall from the grooves 111, as indicated by an arrow G.
Moreover, since the rotary bearings 109 of the movable frame 104 and the grooves 111 are not aligned as shown in FIG. 6A, a moment will be exerted in a closing direction of the movable frame 104 due to a weight of recording paper 7a which has been wound around the winding shaft 105. In addition, a significant change in the weight of the recording paper 7a may affect the opening and closing motions of the movable frame 104. Further, in a case where the rotary bearings 109 and the grooves 111 are aligned in position in order to eliminate this moment as described in Japanese Patent Publication No. 10-101252A, another problem that a layout design may be inflexible and design freedom may be lost.